Ducman

My 34mm Mikunis clear my Rockets and they are shaped similar to CPI. I have the chosen performance pipe seals and they come close to the carb on the left side but still clear.

I would choose the LRD's, but if you need spark arrestors get the FMF's. I dont think you can install any off the shelf spark arrestor on LRD's unless you get pretty creative.

Port Alberni, I'm assuming the "port" means a city at sea level. So in that case no jetting changes necessary.

I'm running a 421 cub setup using 68mm blaster pistons with Mikuni Flatslide TM 38mm carbs. I'm running 35 pilots, P-6 needle jet orafice, needle on the second clip from the top, and 340 mains. Also +10 timming, Rocket inframe drag pipes, & pod filters. Depending on your pipes and intake mods you might even go down to a p-4 (leaner) needle jet orafice. I ran a P-8 with my +4mm stock cylinder dune port motor and they were way to rich for the cubs. Depending on your other mods 350 mains may not be too rich. My motor will run good on mains are a size or 2 big but definitely doesn't like the needle to be too rich.

If your doing the plug chop procedure right and getting a dark ring, even though its not exactly 2mm thick, if its good and dark, your not lean.

Let me run them on my 421 and I'll tell you how they work. :biggrin: A local builder runs LRD big bores on his 421 motor and it seems really snappy into the power a little more down low even with 39mm carbs. My rockets seem like they sort of come on the pipe around 4-6 but real weak and then they kick in HARD at 6K it somewhat helps for trail type riding. But I do know what you mean about jumping and wanting the power but its not there because your around 1-2K to low in the RPM's where a ported stock cylinder motor would still rip.

There are a lot of people running YFZ 450 shocks on banshees, they are longer than stock and do make the front end sit up higher. They are not as good as getting a aftermarket shock valved and sprung for your specific a-arm length, weight, and riding style/type, but they do work prety good especially for heavy riders and cost 1/3 of the price of aftermarket fully adjustable shocks w/tripple rate spring. They are very stiff for the stock a-arms, works good for me at 270#'s, and pretty good for most people on +2 a-arms.

Where's the best place/price to buy them online?

+4 should help your power from bottom to top, you might start hurting top end if you went a lot more than +4. If you are jetted perfectly now, then go up one main size with the +4 timing.

Being a little rich will help stave off detonation so you may want to go up a main size to be safe, but if the engine was already jetted perfectly or a hair on the rich side then no jetting changes will be necessary for increased compression. You will need to use race fuel with 18cc domes though, id go straight 110. Porting will lower static compression if the exhaust port is raised but this can also increase dynamic compression, so dont go off of charts saying 160 psi is OK for pump gas on a ported motor especially for a somewhat top endy port. A trail port maybe.

I run my 21x12x8 extreme's at 3 to 3.5psi Also start in second gear if you have a small front sprocket like 13t or 14t. If you really want to hook up on a 7" swinger you may need to go with 12 paddles but they may want to straighten out your turns under power when you just want to play in the dunes.

with that gearing try some 21x12x8 10 paddle extremes or 22x12x8 10 paddle haulers

I bet if you look around you could find some good used 33-35mm carbs for $200. Get some foam pods to go with them for now like $8 ea. Maybe get some used UPP (stock style) 34mm manifolds for $40-50 or new for $80. It may be a streatch but possibly do-able if you look around, do some fleebay bidding, put a WTB add in the parts forum.

A little trick I have done to clean up the dome surface from carbon or detonation pits is installed a plug in the dome, chucked the plug into a cordless drill and hold some 100 then 400 grit wet/dry emmery paper up to the dome surface while spinning and it cleans it up like new. Try to do it to both domes the same amount and dont touch the bottom edge of the dome (where the o-ring goes). Those domes look pretty Fed up though, but if you want to try to save them give it a try.

FYI, if you mesure the dome with the syringe, use rubbing alchohol. Water has more surface tension so you will get a miniscus (dome) of water and your measure will be as much as 1cc too much. If you measure your squish with the domes installed in the head on the motor and then with the domes out of the head this will tell you if you need to add or subtract cc's from you measure due to the piston going into the dome (positive or negative deck height). You can calculate this small volume like you would calc the volume of a cylinder. These were directions given to me by David Noss for determining the dome volume and I got very close to what he got when I sent the domes and squish measurements to him. If you dont take these differences into account you can be off by more than one cc on a regular motor or several on a stroker/longrod. Even an off the shelf dome marked 20cc could measure 19cc on one motor and 21 on another with the slight inaccuracies of the measurement method and differences in base gasket thicknesses, ect. This is probably why one guy blows his motor up on pump gas with 20cc domes and another guy runs it hard for years. I highly reccomend measureing your squish with the domes on the motor, send the domes and that measure to Noss with what size dome/octane you want to run at what elevation and empasis on low/mid/ or top end power and he will make you a dome that is as perfect as you can get for your application and current engine configuration.

If you have a +5mm rod and run wiseco 795 series pistons (or blaster pistons for big bore) the wrist pin offset is 5mm towards the dome of the piston. This way the total length of the rod + piston is the same as stock. As far as the carbs, might as well get the 34 or 35mm or just stay with the stock carbs. You will be able to get more advice on this forum for tuning the Kehin carbs, but I run the Mikuni Flat Slide TM 34's and I think there a prety easy carb to tune + if you have a large collection of stock main jets they will still work and the jetting #'s are similar to stock carbs.

I would also reccomend getting a good port job on the stock cylinders. Maybe something like the passion "hot MX" 12 port. The cubs power comes on pretty abruptly which is fine for the dunes or drag but doesn't make the best play bike, although I use mine like that but it is a big compramise in the trails. FYI cub cylinders run around $875 and a +4 crank is $450, a +4 cub kit is around $1200. You also need carbs, pipes, swingarm, ect. so $2000+ total.

I noticed you said you removed both plugs to do the test. I've always checked with the plug still in on the opposite side. 105 psi is pretty low for stock at sea level, I'm supprised that both cylinders are so low and still that even. You should kick fast but it shouldn't matter that much because you should only be able to get the guage to go up to a certain point and it wont climb any further. I usually kick at least 10 times but it really only takes a few.

Check the clutch adjustment (clutch arm/pointer on the left side of the case), you may have a hair too much play in the rod that pushes the clutch hub out. If it doesn't push the hub out far enough the friction disks and steals will still rub enough to make you creep forward like that. Be careful though, not enough free play will cause friction on the end of the rod and burn it up which really sucks.

Big Mike, dont get too discouraged by the comments on your post, sometimes these guys are just a bit over zelous only because they love banshees so much. It sounds to me like your just breaking it in right? I wouldn't make any solid judgements on how it is running untill A)you have fully broke in this motor and are certain the jetting is dialed. The couple of built motors I have had both felt like crap on the bottom end at first and it was a combination of needing more break in and jetting. Adding some timing will help for sure, hard to quantify how much but it will be noticeable. You might check your squish, if they are off the shelf domes + a thick cylinder base gasket your squish could be too large and that hurts bottom end or custom domes with a narrow squish band and shallow domes made for top end type settups can hurt bottom end too. Like others have said, your port job may be more top endy than you expected, one builders woods port may quite a bit different than anothers. I say whatever, more top end = more fun in my book anyway, just makes the trails more exciting. I have a local builder that is prety knowledgeable, builds some incredible dune bikes and drag motors, has a dyno, but it you try to get him to build something much different from his usual build, with way different components that he has never tried and tested before, and don't spend $10 million dollars for him to tinker and screw with tuneing and playing with the setup for a week, you can end up with a sac of shit.

You should kill the KFX if you can get decent traction, if its on a very loose surface like a gravel covered dirt road it wont be so easy. On pavement he'll be sucking 2 stroke fumes.

MB Quart's are real nice and can go very loud with a clean amp. The infinity components sound good but I wouldn't run them w/o an amp. For a cheaper set of speakers, I had a set of Polk 6.5" with the tweater mounted/suspended above the cone and they sounded great.

-20*C = -68*F Dude! Thats insane. Do you live above the arctic circle or something? I woudn't even leave my house if it was even below 20*F. As a rule of thumb if you are jetted perfectly then every time you drop 30*F approx 16.6*C then go up one main size. That is typically only used from 90*F down to 0*F so summer jeting could be 3 main sizes leaner than winter jetting in very cold areas. I don't know how accurately that applies to -68*F that would be 5 main sizes larger than summer jetting if it is 90*F. As for the air temp rich/ lean question, when the air is cold and dense your motor pulls in more total air molecules. The main jet in the carb still puts out the same amount of fuel so the combined mixture is leaner; same amount of fuel + more air.

Vitos are decent, they are made by wiseco.

The orange outer sleeve your talking about should help keep your filters clean for longer. I would not put any oil on the outer sleeve and very little on the filter itself in the sand. When the outer sleeve gets covered in sand just pull it off and run only the filter iself. The K&N fabric type outerwear will totally clog up if it gets foam filter oil on it, I wouldn't use it at all with a foam filter. Also if you get UNI foam filter oil in the spray can it is not as sticky as some foam filter oils. Some foam filter oil like what Yamaha makes for the stock filter is so sticky it will have the whole sand dune stuck to your filters.